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| United States Patent |
6,022,665
|
|
Watanabe
, et al.
|
February 8, 2000
|
Polymers and chemically amplified positive resist compositions
Abstract
The invention provides a novel polymer comprising a recurring unit of
formula (1) wherein R.sup.1 is hydrogen or methyl, R.sup.2 is hydrogen or
acid labile group, at least one R.sup.2 being hydrogen and at least one
R.sup.2 being an acid labile group, and n=2 or 3. The polymer's Mw is
3,000-300,000. Blending the polymer as a base resin with an organic
solvent and a photoacid generator yields a chemically amplified positive
resist composition.
##STR1##
| Inventors:
|
Watanabe; Osamu (Nakakubiki-gun, JP);
Takeda; Yoshihumi (Nakakubiki-gun, JP);
Tsuchiya; Junji (Nakakubiki-gun, JP);
Ishihara; Toshinobu (Nakakubiki-gun, JP)
|
| Assignee:
|
Shin-Etsu Chemical Co., Ltd. (Tokyo, JP)
|
| Appl. No.:
|
109084 |
| Filed:
|
July 2, 1998 |
Foreign Application Priority Data
| Current U.S. Class: |
430/270.1; 430/914 |
| Intern'l Class: |
G03C 001/492 |
| Field of Search: |
430/270.1,914
|
References Cited
U.S. Patent Documents
| 4491628 | Jan., 1985 | Ito et al. | 430/176.
|
| 4678737 | Jul., 1987 | Schneller et al. | 430/270.
|
| 4869994 | Sep., 1989 | Gupta et al. | 430/197.
|
| 4963596 | Oct., 1990 | Lindert et al. | 526/313.
|
| 5084490 | Jan., 1992 | McArdle et al. | 522/181.
|
| 5252435 | Oct., 1993 | Tani et al. | 430/325.
|
| 5324804 | Jun., 1994 | Steinmann | 526/313.
|
| 5824451 | Oct., 1998 | Aoai et al. | 430/270.
|
| Foreign Patent Documents |
| 0 002 456 | Jun., 1979 | EP.
| |
| 0 002 887 | Jul., 1979 | EP.
| |
Primary Examiner: Baxter; Janet
Assistant Examiner: Ashton; Rosemary
Attorney, Agent or Firm: Millen, White, Zelano, & Branigan, P.C.
Parent Case Text
This is a division of application Ser. No. 08/630,633 filed Apr. 11, 1996.
Claims
We claim:
1. A chemically amplified positive resist composition comprising
(A) an organic solvent,
(B) a base resin in the form of a polymer comprising a recurring unit of at
least one type of the following general formula (1) and having a weight a
average molecular weight of 3,000 to 300,000:
##STR23##
wherein R.sup.1 is a hydrogen atom or methyl group, R.sup.2 is a hydrogen
atom or acid labile group, at least one R.sup.2 being a hydrogen atom and
at least one R.sup.2 being an acid labile group, and letter n is equal to
2or 3, and
(C) a photoacid generator.
2. A chemically amplified positive resist composition according to claim 1,
further comprising
(D) a dissolution regulator in the form of a compound having a weight
average molecular weight of 100 to 1,000 and at least two phenolic
hydroxyl groups in a molecule, the hydrogen atom of the phenolic hydroxyl
group being replaced by an acid labile group in an average amount of 10 to
100% of the entire phenolic hydroxyl groups.
3. The chemically amplified positive resist composition of claim 2 wherein
(D) dissolution regulator is at least one compound selected from phenolic
hydroxyl group-bearing compounds of the following formulae (4) to (14):
##STR24##
wherein R.sup.8 and R.sup.9 are independently selected from the class
consisting of a hydrogen atom and normal or branched alkyl and alkenyl
groups of 1 to 8 carbon atoms,
R.sup.10 is selected from the class consisting of a hydrogen atom, normal
or branched alkyl and alkenyl groups of 1 to 8 carbon atoms, and
--(R.sup.14).sub.z --COOH,
R.sup.11 and R.sup.12 are independently selected from the class consisting
of an alkylene group of 1 to 10 carbon atoms, arylene group, carbonyl
group, sulfonyl group, oxygen atom, and sulfur atom,
R.sup.13 is selected from the class consisting of alkyl and alkenyl groups
of 1 to 8 carbon atoms, hydrogen atom, hydroxyl-substituted phenyl group,
and hydroxyl-substituted naphthyl group,
R.sup.14 is a normal or branched alkylene group of 1 to 10 carbon atoms,
letter h is an integer of 0 to 3,
z is equal to 0 or 1,
x, y, x', y', x", and y" are such numbers in the range: x+y=8, x'+y'=5, and
x"+y"=4 that at least one hydroxyl group is container in each phenyl
skeleton,
the hydrogen atom of the phenolic hydroxyl group of said at least one
compound being replaced by an acid labile group.
4. The composition of claim 2 wherein;
the organic solvent (A) is present in an amount of 200 to 1000 parts by
weight per 100 parts by weight of the base resin (B);
the photoacid generator (C) is present in an amount of 1 to 20 parts by
weight per 100 parts by weight of the base resin (B); and
the dissolution regulator (D) is present in an amount of 5 to 50 parts by
weight per 100 parts by weight of the base resin (B).
5. A chemically amplified positive resist composition according to claim 1,
further comprising
(E) a dissolution regulator in the form of a compound having a weight
average molecular weight of 1,000 to 3,000 and a phenolic hydroxyl group
in a molecule, the hydrogen atom of the phenolic hydroxyl group being
partially replaced by an acid labile group in an average amount of more
than 0% to 60% of the entire phenolic hydroxyl group.
6. The composition of claim 5 wherein;
the organic solvent (A) is present in an amount of 200 to 1000 parts by
weight per 100 parts by weight of the base resin (B);
the photoacid generator (C) is present in an amount of 1 to 20 parts by
weight per 100 parts by weight of the base resin (B); and
the dissolution regulator (E) is present in an amount of 1 to 50 parts by
weight per 100 parts by weight of the base resin (B).
7. The chemically amplified positive resist composition of claim 1 further
comprising (F) a basic compound as an additive.
8. The chemically amplified positive resist composition claims 1 wherein
(C) photoacid generator is an onium salt.
9. The composition of claim 1 wherein;
the organic solvent (A) is present in an amount of 200 to 1000 parts by
weight per 100 parts by weight of the base resin (B); and
the photoacid generator (C) is present in an amount of 1 to 20 parts by
weight per 100 parts by weight of the base resin (B).
10. A composition according to claim 1, wherein the base resin (B) polymer
is a monodisperse polymer having a molecular weight dispersity of 1.0 to
1.5.
11. A chemically amplified positive resist composition comprising
(A) an organic solvent,
(B) a base resin in the form of comprising unit of at least type of the
following general formula (I) and having a weight average molecular weight
of 3,000 to 300,000;
##STR25##
wherein R.sup.1 is a hydrogen atom or methyl group, R.sup.2 is a hydrogen
atom or acid labile group, at least one R.sup.2 being a hydrogen atom and
at least one R.sup.2 being an acid labile group, and letter n is equal to
2or 3,
(C) a photoacid generator,
(D) a dissolution regulator in the form of a compound having a weight
average molecular weight of 100 to 1,000 and at least two phenolic
hydroxyl groups in a molecule, the hydrogen atom of the phenolic hydroxyl
group being replaced by an acid labile group in an average amount of 10 to
100% of the entire phenolic hydroxyl groups, and
(E) another dissolution regulator in the form of a compound having a weight
average molecular weight of more than 1,000 to 3,000 and a phenolic;
hydroxyl group in a molecule, the hydrogen atom of the phenolic hydroxyl
group being partially replaced by an acid labile group in an average
amount of more than 0% to 60% of the entire phenolic hydroxyl groups.
12. The chemically amplified positive resist composition of claim 11
wherein (D) dissolution regulator is at least one compound selected from
phenolic hydroxyl group-bearing compounds of the following formulae (4) to
(14):
##STR26##
wherein R.sup.8 and R.sup.9 are independently selected from the class
consisting of a hydrogen atom and normal or branched alkyl and alkenyl
groups of 1 to 8 carbon atoms,
R.sup.10 is selected from the class consisting of a hydrogen atom, normal
or branched alkyl and alkenyl groups of 1 to 8 carbon atoms, and
--(R.sup.14).sub.z --COOH,
R.sup.11 and R.sup.12 are independently selected from the class consisting
of an alkylene group of 1 to 10 carbon atoms, arylene group, carbonyl
group, sulfonyl group, oxygen atom, and sulfur atom,
R.sup.13 is selected from the class consisting of alkyl and alkenyl groups
of 1 to 8 carbon atoms, hydrogen atom, hydroxyl-substituted phenyl group,
and hydroxyl-substituted naphthyl group,
R.sup.14 is a normal or branched alkylene group of 1 to 10 carbon atoms,
letter h is an integer of 0 to 3,
z is equal to 0 or 1,
x, y, x', y', x", and y" are such numbers in the range: x+y=8, x'+y'=5, and
x" +y"=4 that at least one hydroxyl group is contained in each phenyl
skeleton,
the hydrogen atom of the phenolic hydroxyl group of said at least one
compound being replaced by an acid labile group.
13. The chemically amplified positive resist composition of claim 11
wherein (E) dissolution regulator is at least one compound having a
recurring unit of the following general formula (15):
##STR27##
wherein R is an acid labile group, and letters b and c are numbers
satisfying 0<b/(b+c).ltoreq.0.6.
14. The composition of claim 11 wherein;
the organic solvent (A) is present in an amount of 200 to 1000 parts by
weight per 100 parts by weight of the base resin (B);
the photoacid generator (C) is present in an amount of 1 to 20 parts by
weight per 100 parts by weight of the base resin (B);
the dissolution regulator (D) is present in an amount of 5 to 50 parts by
weight per 100 parts by weight of the base resin (B); and
the dissolution regulator (E) is present in an amount of 1 to 50 parts by
weight per 100 parts by weight of the base resin (B).
15. The composition according to claim 11, wherein at least one acid labile
group in the base resin is selected from those of the following formulae
(16) and (17), normal, branched or cyclic alkyl groups of 1 to 6 carbon
atoms, tetrahydropyrany, tetrafuranyl and trialkylsilyl groups;
##STR28##
wherein R.sup.15 and R.sup.16 are independently a hydrogen atom or a
normal or branched alkyl group of 1 to 6 carbon atoms, R.sup.17 is a
normal, branched or cyclic alkyl group of 1 to 10 carbon atoms, R.sup.18
is a hydrogen atom or a normal, branched or cyclic alkyl group of 1 to 6
carbon atoms, and letter a is equal to 0 or 1.
16. The composition according to claim 11, wherein the polymer of base
resin (B) is a monodisperse polymer having a molecular weight dispersity
of 1.0 to 1.5.
17. A chemically amplified positive resist composition comprising
(A) an organic solvent,
(B) a base resin in the form of a polymer comprising a recurring unit of at
least one type of the following general formula (1) and having a weight
average molecular weight of 3,000 to 300,000:
##STR29##
wherein R.sup.1 is a hydrogen atom or methyl group, R.sup.2 is a hydrogen
atom or acid labile group, at least one R.sup.2 being a hydrogen atom and
at least one R.sup.2 being an acid labile group, and letter n is equal to
2 or 3,
(C) a photoacid generator, and
(D) a dissolution regulator in the form of a compound having a weight
average molecular weight of 100 to 1,000 and at least two phenolic
hydroxyl groups in a molecule, the hydrogen atom of the phenolic hydroxyl
group being replaced by an acid labile group in an average amount of 10 to
100% of the entire phenolic hydroxyl groups, and
(E) another dissolution regulator in the form of a compound having a weight
average molecular weight of more than 1,000 to 3,000 and a phenolic
hydroxyl group in a molecule, the hydrogen atom of the phenolic hydroxyl
group being partially replaced by an acid labile group in an average
amount of more than 0% to 60% of the entire phenolic hydroxyl groups,
wherein (E) dissolution regulator is at least ore compound having a
recurring unit of the following general formula (15):
##STR30##
wherein R is an acid labile group, and letter b and c are number
satisfying 0<b/(b+c).ltoreq.0.6.
18. The composition according to claim 17, wherein at least one acid labile
group in the base resin is selected from those of the following formulae
(16) and (17), normal, branched or cyclic alkyl groups of 1 to 6 carbon
atoms, tetrahydropyrinyl, tetrafuranyl and trialkylsilyl groups;
##STR31##
wherein R.sup.15 and R.sup.16 are independently a hydrogen atom or a
normal or branched alkyl group of 1 to 6 carbon atoms, R.sup.7 is a
normal, branched or cyclic alkyl group of 1 to 10 carbon atoms, R.sup.18
is a hydrogen atom or a normal, branched or cyclic alkyl group of 1 to 6
carbon atoms, and letter a is equal to 0 or 1.
19. The composition according to claim 17, wherein the polymer of base
resin (B) is a monodisperse polymer having a molecular weight dispersity
of 1.0 to 1.5.
20. A chemically amplified positive resist composition comprising,
(A) an organic solvent,
(B) a base resin in the form of a polymer of the following general formula
(2) and having a weight average molecular weight of 3,000 to 300,000:
##STR32##
wherein R.sup.1 is independently a hydrogen atom or methyl group,
R.sup.2 is a hydrogen atom or acid labile group, at least one R.sup.2 being
a hydrogen atom and at least one R.sup.2 being an acid labile group,
R.sup.3 is an acid labile group,
R.sup.4 is a hydrogen atom,
R.sup.5 is a group represented by
##STR33##
wherein X is a hydrogen atom or acid labile group and R.sup.6 is a
hydrogen atom or an alkyl group of 1 to 6 carbon atoms, or
R.sup.4 and R.sup.5, taken together, may form --C(O)--O--C(O), each of the
units may be of one or more types,
letter n is equal to 2 or 3,
each of m and K is equal to 1,2 or 3,
p and q are positive numbers and r and s are 0 or positive numbers
satisfying 0<(p+q)/(p+q+r+s).ltoreq.1 and the sum of p+q+r+s is a
sufficient number to give the weight average molecular weight and
(C) a photoacid generator.
21. The composition according to claim 20, wherein at least one acid labile
group in the base resin is selected from those of the following formulae
(16) and (17), normal, branched or cyclic alkyl groups of 1 to 6 carbon
atoms, tetrahydropyranyl, tetrafuranyl and trialkylsilyl groups;
##STR34##
wherein R.sup.15 and R.sup.16 are independently a hydrogen atom or a
normal or branched alkyl group of 1 to 6 carbon atoms, R.sup.17 is a
normal, branched or cyclic alkyl group of 1 to 10 carbon atoms, R.sup.18
is a hydrogen atom or a normal, branched or cyclic alkyl group of 1 to 6
carbon atoms, and letter a is equal to 0 or 1.
22. The composition according to claim 20, wherein the polymer of base
resin (B) is a monodisperse polymer having a molecular weight dispersity
of 1.0 to 1.5.
23. A chemically amplified positive resist composition, comprising
(A) an organic solvent,
(B) a base resin in the form of a polymer of the following general formula
(3) and having a weight average molecular weight of 3,000 to 300,000:
##STR35##
wherein R.sup.1, R.sup.3, R.sup.4, and R.sup.5 are as defined in claim 20,
R.sup.7 is an acid labile group,
each of the units may be of one or more types,
letters n and m are as defined in claim 20,
t and q are positive numbers and r and s are 0 or positive numbers
satisfying 0<(t+q)/(t +q+r+s).ltoreq.0.7 and the sum of t+q+r+s is a
sufficient number to give the weight average molecular weight, and
(C) a photoacid generator.
24. The composition according to claim 23, where in at least one acid
labile group in the base resin is selected from those of the following
formulae (16) and (17), normal, branched or cyclic alkyl groups of 1 to 6
carbon atoms, tetrahydropyranyl, tetrafuranyl and trialkylsilyl groups;
##STR36##
wherein R.sup.15 and R.sup.16 are independently a hydrogen atom or a
normal or branched alkyl group of 1 to 6 carbon atoms, R.sup.17 is a
normal, branched or cyclic alkyl group of 1 to 10 carbon atoms, R.sup.18 s
is a hydrogen atom or a normal, branched or cyclic alkyl group of 1 to 6
carbon atoms, and letter a is equal to 0 or 1.
25. The composition according to claim 23, wherein the polymer of base
resin (B) is a monodisperse polymer having a molecular weight dispersity
of 1.0 to 1.5.
26. A chemically amplified positive resist composition comprising
(A) an organic solvent,
(B) a base resin in the form of a polymer comprising a recurring unit of at
least one type of the following general formula (1) and having a weight
average molecular weight of 3,000 to 300,000:
##STR37##
wherein R.sup.1 is a hydrogen atom or methyl group, R.sup.2 is a hydrogen
atom or acid labile group, at least one R.sup.2 being a hydrogen atom and
at least one R.sup.2 being an acid labile group, and letter n is equal to
2 or 3, and
(C) a photoacid generator,
said acid labile group in the base resin polymer being selected from the
group consisting of groups of the following formulae (16) and (17),
tert-butyl group, cyclohexyl group, tetrahydropyranyl group, tetrafuranyl
group and trialkylsilyl group whose alkyl moiety has 1 to 6 carbon atoms:
##STR38##
wherein R.sup.15 and R.sup.16 are independently a hydrogen atom or a
normal or branched alkyl group of 1 to 6 carbon atoms, R.sup.17 is a
normal, branched or cyclic alkyl group of 1 to 10 carbon atoms, R.sup.18
is a hydrogen atom or a normal, branched or cyclic alkyl group of 1 to 6
carbon atoms, and letter a is equal to 0 or 1.
27. The composition according to claim 26, wherein the polymer of base
resin (B) is a monodisperse polymer having a molecular weight dispersity
of 1.0 to 1.5.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a polymer and a chemically amplified positive
resist composition containing the same. More particularly, it relates to a
polymer which is blended as a base resin with resist components to form a
chemically amplified positive resist composition which has significantly
improved alkali dissolution rate contrast before and after exposure, high
sensitivity, and high resolution and is thus suitable as a fine
pattern-forming material in the manufacture of ultra-LSI's.
2. Prior Art
As the LSI technology tends toward higher integration and higher speed,
further refinement of pattern rules is required. Under the circumstances,
deep-ultraviolet lithography is regarded promising as fine patterning
technology of the next generation. The deep-UV lithography is capable of
working on the order of less than 0.5 .mu.m. If a less light absorbing
resist is used, it is possible to form a pattern having a side wall nearly
perpendicular to the substrate.
There were recently developed positive working resist materials which
undergo acid-catalyzed chemical amplification as disclosed in Japanese
Patent Publication (JP-B) No. 27660/1990 (corresponding to U.S. Pat. No.
4,491,628) and Japanese Patent Application Kokai (JP-A) No. 27829/1988
(corresponding to EP 249139). Because of many advantages including
sensitivity, resolution, and dry etching resistance, the chemically
amplified resist materials are regarded promising for deep-ultraviolet
lithography using a high intensity KrF excimer laser as a source of
deep-ultraviolet radiation.
Known chemically amplified positive working resist materials include a
two-component system comprising a base polymer and a photoacid generator
and a three-component system comprising a base polymer, a photoacid
generator, and a dissolution regulator having an acid labile group. For
example, JP-A 115440/1987 (corresponding to U.S. Pat. No. 4,603,101)
discloses a resist composition comprising poly-4-tert-butoxystyrene and a
photoacid generator. There are proposed analogous resist compositions.
JP-A 223858/1991 (corresponding to U.S. Pat. No. 5,252,435) discloses a
two-component resist composition comprising a resin having a tert-butoxy
group in a molecule and a photoacid generator. JP-A 211258/1992 discloses
a two-component resist composition comprising a polyhydroxystyrene having
a methyl, isopropyl, tert-butyl, tetrahydropyranyl or trimethylsilyl group
and a photoacid generator. Further, JP-A 100488/1994 (corresponding to
U.S. Pat. No. 5,324,804) discloses a resist composition comprising a
polydihydroxystyrene derivative such as
poly(3,4-bis(2-tetrahydropyranyloxy)styrene),
poly(3,4-bis(tert-butoxycarbonyloxy)styrene), and
poly(3,5-bis(2-tetrahydropyranyloxy)styrene) and a photoacid generator.
These resist compositions, however, are not necessarily satisfactory in
that some are low in contrast of a dissolution rate of a resist film, some
have unsatisfactory sensitivity and resolution, and some are less process
adaptable. None of them have been used in practice. There is a need to
overcome these problems.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a polymer which is blended
as a base resin with resist components to form a chemically amplified
positive resist composition which is improved in sensitivity, resolution,
latitude of exposure, and process adaptability over the conventional
resist compositions.
Another object of the present invention is to provide a chemically
amplified positive resist composition using the polymer as a base resin.
We have found that a novel polymer having a recurring unit of the general
formula (1) or a novel polymer of the general formula (2) or (3) to be
defined below, all having a weight average molecular weight of 3,000 to
300,000, can be formed by a method to be described later. A chemically
amplified positive resist composition is obtained using any of these
polymers as a base resin. More particularly, chemically amplified positive
resist compositions are obtained by adding a photoacid generator to the
polymer, or by adding a photoacid generator and a dissolution regulator to
the polymer, or by adding a photoacid generator, a dissolution regulator,
and a basic compound to the polymer. These resulting chemically amplified
positive resist compositions afford resists which have high sensitivity,
high resolution, improved latitude of exposure, and improved process
adaptability and are well suited for practical use and advantageously used
in precise fine patterning, especially in ultra-LSI manufacture.
The formulae (1) to (3) are shown below.
##STR2##
R.sup.1 is a hydrogen atom or methyl group, R.sup.2 is a hydrogen atom or
acid labile group, at least one R.sup.2 being a hydrogen atom and at least
one R.sup.2 being an acid labile group, and
letter n is equal to 2 or 3.
##STR3##
R.sup.1 is independently a hydrogen atom or methyl group, R.sup.2 is a
hydrogen atom or acid labile group, at least one R.sup.2 being a hydrogen
atom and at least one R.sup.2 being an acid labile group,
R.sup.3 is an acid labile group,
R.sup.4 is a hydrogen atom,
R.sup.5 is a group represented by
##STR4##
wherein X is a hydrogen atom or acid labile group and R.sup.6 is a
hydrogen atom or an alkyl group of 1 to 6 carbon atoms, or
R.sup.4 and R.sup.5, taken together, may form --C(O)--O--C(O)--,
each of the units may be of one or more types,
letter n is equal to 2 or 3,
each of m and k is equal to 1, 2 or 3,
p and q are positive numbers and r and s are 0 or positive numbers
satisfying 0<(p+q)/(p+q+r+s) .ltoreq.1 and the sum of p+q+r+s is a
sufficient number to give a weight average molecular weight in the
above-defined range.
##STR5##
R.sup.1, R.sup.3, R.sup.4, and R.sup.5 are as defined above, R.sup.7 is an
acid labile group,
each of the units may be of one or more types,
letters n and m are as defined above,
t and q are positive numbers and r and s are 0 or positive numbers
satisfying 0<(t+q)/(t+q+r+s).ltoreq.0.7 and the sum of t+q+r+s is a
sufficient number to give a weight average molecular weight in the
above-defined range.
In the polymer having a recurring unit of formula (1), some phenolic
hydroxyl groups are protected with acid labile groups. When the polymer is
blended in a chemically amplified positive resist composition as an
alkali-soluble resin, phenolic hydroxyl groups remaining in its molecule
form a strong hydrogen bond between its molecules or between its molecule
and a photoacid generator and dissolution regulator. In a patterning
process including exposure, heating and developing steps, the rate of
dissolution in aqueous base solution is strictly controlled in an
unexposed area. In an exposed area, an acid labile group moiety of the
base resin or matrix is decomposed to cut off the hydrogen bond whereby
the rate of dissolution in aqueous base solution is rapidly accelerated.
It is noted that polymeric polyhydric hydroxystyrene derivatives in which
all phenolic hydroxyl groups of polyhydric hydroxystyrene are protected
with acid labile groups such as tert-butoxycarbonyl groups (often
abbreviated as tert-BOC groups), for example,
poly(di-tert-butoxycarbonyloxystyrene) are well known in the art.
According to our experiment, these fully protected polyhydroxystyrene
derivatives form a weak bond to the substrate because of the absence of
phenolic hydroxyl groups. The polyhydric hydroxystyrene polymer whose
phenolic hydroxyl groups are all protected with acid labile groups such as
tert-BOC groups has the problem that it gives off a large amount of
decomposed products (e.g., isobutylene and carbon dioxide) after exposure,
leaving scum.
Conventional partially tert-BOC-incorporated polyhydroxystyrenes have a
relatively low rate of dissolution in alkali of 3,000 .ANG./sec. after
decomposition whereas partially tert-BOC-incorporated polyhydric
hydroxystyrene polymers according to the invention have a rate of
dissolution of 10,000 .ANG./sec. Thus a polymer of the invention and a
resist composition containing the same are highly effective.
A chemically amplified positive resist composition using a polymer having a
recurring unit of formula (1) affords a resist film which has an increased
contrast of a rate of dissolution in aqueous basic solution between
exposed and unexposed areas as compared with the conventional resists and
consequently has high sensitivity and high resolution. The same applies to
compositions using polymers of formulae (2) and (3). In addition to the
above-mentioned advantages, the chemically amplified positive resist
compositions having the copolymers blended as a base resin permit resist
patterns to be controlled in size and configuration in terms of their
composition and are well process adaptable.
In one aspect, the present invention is directed to a polymer. In a first
form, there is provided a polymer comprising a recurring unit of at least;
one type of formula (1) and having a weight average molecular weight of
3,000 to 300,000.
In a second form, there is provided a polymer of formula (2) and having a
weight average molecular weight of 3,000 to 300,000.
In a third form, there is provided a polymer of formula (3) and having a
weight average molecular weight of 3,000 to 300,000.
Preferably the polymers are mono-disperse polymers having a molecular
weight dispersity of 1.0 to 1.5.
In another aspect, the present invention is directed to a chemically
amplified positive resist composition. In a first form, there is provided
a chemically amplified positive resist composition comprising
(A) an organic solvent,
(B) a base resin in the form of a polymer as defined above, and
(C) a photoacid generator which is preferably an onium salt.
In a second form, there is provided a chemically amplified positive resist
composition comprising components (A), (B), and (C), and (D) a dissolution
regulator in the form of a compound having a weight average molecular
weight of 100 to 1,000 and at least two phenolic hydroxyl groups in a
molecule, the hydrogen atom of the phenolic hydroxyl group being replaced
by an acid labile group in an average amount of 10 to 100% of the entire
phenolic hydroxyl groups. The dissolution regulator (D) is preferably at
least one compound selected from phenolic hydroxyl group-bearing compounds
of formulae (4) to (14) to be described later, the hydrogen atom of the
phenolic hydroxyl group of the at least one compound being replaced by an
acid labile group.
In a third form, there is provided a chemically amplified positive resist
composition comprising components (A), (B), (C), and (E) a dissolution
regulator in the form of a compound having a weight average molecular
weight of more than 1,000 to 3,000 and a phenolic hydroxyl group in a
molecule, the hydrogen atom of the phenolic hydroxyl group being partially
replaced by an acid labile group in an average amount of more than 0% to
60% of the entire pherolic hydroxyl groups. The dissolution regulator (E)
is preferably at least one compound having a recurring unit of formula
(15) to be described later.
A chemically amplified positive resist composition comprising components
(A), (B), (C), (D), and (E) is also contemplated.
Each of these chemically amplified positive resist compositions may further
have blended therein (F) a basic compound.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIG. 1 is a graph showing a GPC elution curve of the polymer obtained in
Synthesis Example 14.
FIG. 2 is a graph showing a GPC elution curve of the polymer obtained in
Synthesis Example 15.
DETAILED DESCRIPTION OF THE INVENTION
In the first aspect, the present invention in the first form provides a
polymer comprising a recurring unit of at least one type of the general
formula (1):
##STR6##
wherein R.sup.1 is a hydrogen atom or methyl group,
R.sup.2 is a hydrogen atom or acid labile group, at least one R.sup.2 being
a hydrogen atom and at least one R.sup.2 being an acid labile group, and
letter n is equal to 2 or 3.
The present invention in the second form provides a copolymer of the
general formula (2):
##STR7##
wherein R.sup.1 is independently a hydrogen atom or methyl group,
R.sup.2 is a hydrogen atom or acid labile group, at least one R.sup.2 being
a hydrogen atom and at least one R.sup.2 being an acid labile group,
R.sup.3 is an acid labile group,
R.sup.4 is a hydrogen atom,
R.sup.5 is a group represented by
##STR8##
wherein X is a hydrogen atom or acid labile group and R.sup.6 is a
hydrogen atom or an alkyl group of 1 to 6 carbon atoms (e.g., methyl,
ethyl, propyl, and butyl), or
R.sup.4 and R.sup.5, taken together, may form --C(O)--O--C(O)--,
each of the units may be of one or more types,
letter n is equal to 2 or 3,
each of m and k is equal to 1, 2 or 3,
p and q are positive numbers and r and s are 0 or positive numbers
satisfying 0<(p+q)/(p+q+r+s).ltoreq.1 and the sum of p+q+r+s is a
sufficient number to give the weight average molecular weight.
The present invention in the third form provides a copolymer of the general
formula (3):
##STR9##
wherein R.sup.1, R.sup.3, R.sup.4, and R.sup.5 are as defined above,
R.sup.7 is an acid labile group,
each of the units may be of one or more types,
letters n and m are as defined above,
t and q are positive numbers and r and s are 0 or positive numbers
satisfying 0<(t+q)/(t+q+r+s).ltoreq.0.7 and the sum of t+q+r+s is a
sufficient number to give the weight average molecular weight.
In formulae (1) to (3), the acid labile group may be selected from various
such groups. Preferred acid labile groups are groups of the following
formulae (16) and (17), normal, branched or cyclic alkyl groups of 1 to 6
carbon atoms, tetrahydropyranyl, tetrafuranyl and trialkylsilyl groups.
##STR10##
In formulae (16) and (17), R.sup.15 and R.sup.16 are independently a
hydrogen atom or a normal or branched alkyl group of 1 to 6 carbon atoms,
R.sup.17 is a normal, branched or cyclic alkyl group of 1 to 10 carbon
atoms, R.sup.18 is a hydrogen atom or a normal, branched or cyclic alkyl
group of 1 to 6 carbon atoms, and letter a is equal to 0 or 1.
Examples of the normal and branched alkyl groups include methyl, ethyl,
propyl, isopropyl, n-butyl, iso-butyl, and tert-butyl groups. Cyclohexyl
is a typical cyclic alkyl group. Examples of the acid labile group of
formula (16) include methoxyethyl, ethoxyethyl, n-propoxyethyl,
iso-propoxyethyl, n-butoxyethyl, iso-butoxyethyl, tert-butoxyethyl,
cyclohexyloxyethyl, methoxypropyl, ethoxypropyl, 1-methoxy-1-methylethyl,
and 1-ethoxy-1-methylethyl groups. Examples of the acid labile group of
formula (17) include tert-butoxycarbonyl and tert-butoxycarbonylmethyl
groups. Examples of the trialkylsilyl group include those trialkylsilyl
groups whose alkyl moiety has 1 to 6 carbon atoms, such as trimethylsilyl
and tri-tert-butyldimethylsilyl groups.
In the polymers having a recurring unit of formula (1), the recurring unit
may be of one or more types. That is, the polymer may comprise either
recurring units of one type or recurring units of two or more types. The
polymer of formula (2) consist essentially of units of formulae (2a),
(2b), (2c) and (2d) shown below. The polymer of formula (3) consist
essentially of units of formulae (3a), (3b), and (3d) shown below. Each of
these units may be of one or more types as long as these types are within
the definition of that unit.
##STR11##
It is preferred that each of the polymers of the invention contain acid
labile groups of two or more types when properties of a chemically
amplified positive resist composition having the polymer blended as a base
resin are taken into account. For the acid labile groups of two or more
types, a combination of an alkoxyalkyl group of formula (16) and a group
of formula (17) is preferred.
In formulae (1) to (3), n is equal to 2 or 3. For the following reason, 2
or 3 is selected for n. Decomposition of an acid labile group leaves a
hydroxyl group. As the number of hydroxyl groups increases to 2 or 3,
acidity increases and arbitrary control of an alkali dissolution rate
becomes possible. Letter m is 1, 2 or 3, with m=2 being preferred for ease
of synthesis and control of an alkali dissolution rate.
In formula (2), p and q are positive numbers and r and s are 0 or positive
numbers satisfying 0<(p+q)/(p+q+r+s).ltoreq.1, preferably
0<(p+q)/(p+q+r+s).ltoreq.0.7, more preferably
0.05.ltoreq.(p+q)/(p+q+r+s).ltoreq.0.7. In formula (3), t and are positive
numbers and r and s are 0 or positive numbers satisfying
0<(t+q)/(t+q+r+s).ltoreq.0.7, more preferably
0.05.ltoreq.(t+q)/(t+q+r+s).ltoreq.0.7. If p, q or t is 0, the results are
less contrast of alkali dissolution rate and poor resolution. If
(p+q)/(p+q+r+s) or (t+q)/(t+q+r+s) is more than 0.7, the resist film would
undergo thickness variation, internal stressing or bubbling upon alkali
development and lose its adhesion to the underlying substrate due to
lesser hydrophilic groups.
The ratio of p or t to the sum of (p+q+r+s) or (t+q+r+s) is preferably
between 0.05 and 0.8 in molar ratio, especially between 0.05 and 0.5. The
ratio of q to the sum of (p+q+r+s) or (t+q+r+s) is preferably between 0.2
and 0.95 in molar ratio, especially between 0.3 and 0.95. The preferred
range of r and s is 0 to 0.5, especially 0.05 to 0.3 for both.
In the polymers of formulae (1) to (3), the content of acid labile group
affects the contrast of a dissolution rate of resist film and is closely
related to properties of resist film such as pattern size control and
pattern configuration.
The polymers of formulae (1) to (3) should have a weight average molecular
weight of 3,000 to 300,000, preferably 3,000 to 30,000 (the measurement of
weight average molecular weight will be described later). With a weight
average molecular weight of less than 3,000, resists would be less
resistant to heat. With a weight average molecular weight of more than
300,000, alkali solubility lowers and a footing phenomenon would be likely
to occur after patterning. In formulae (2) and (3), the sum of (p+q+r+s)
or (t+q+r+s) is a sufficient number to give a weight average molecular
weight within this range.
A polymer having a wide molecular weight dispersity (Mw/Mn) contains more
polymers of low molecular weight and high molecular weight. The presence
of more polymers of low molecular weight can lead to a loss of heat
resistance. The presence of more polymers of high molecular weight which
are less soluble in alkali can cause a footing phenomenon after
patterning. As a consequence, the influence of a molecular weight and its
dispersity becomes greater as the pattern rule becomes finer. In order
that a resist material be advantageously used in patterning features to a
finer size, the polymer should preferably be a monodisperse one having a
molecular weight dispersity of 1.0 to 1.5, especially 1.0 to 1.3.
The polymer comprising a recurring unit of formula (1) can be prepared by
radical polymerization or living anion polymerization of a monomer of the
following formula (i). Alternatively, the polymer can be prepared by
effecting radical polymerization or living anion polymerization of a
monomer of the following formula (ii), partially hydrolyzing the resulting
polymer, and partially deprotecting its protective group R.sup.7 (that is,
deprotecting so as to leave at least one protective group and generate at
least one hydroxyl group). Moreover, the polymer can also be prepared by
copolymerizing at least two types of monomers of formula (i) or (ii).
Where monomers of formula (ii) are used, subsequent partial hydrolysis
yields a polymer comprising at least two types of units of formula (1).
##STR12##
R.sup.1, R.sup.2, R.sup.7, and n are as defined previously.
In preparing the polymer of formula (2), radical polymerization or living
anion polymerization of a monomer of formula (i) with a monomer of the
following formula (iii) and optionally a monomer of formula (iv) and/or a
monomer of formula (v) may be used. In preparing the polymer of formula
(3), radical polymerization or living anion polymerization of a monomer of
formula (ii) with a monomer of formula (iii) and optionally a monomer of
formula (iv) and/or a monomer of formula (v) may be used. For each of
these monomers, two or more types can be used.
##STR13##
R.sup.1, R.sup.3, R.sup.4, R.sup.5, m, and k are as defined previously.
When the polymer is applied to resist materials patternable to a finer
pattern rule, a monodisperse polymer is preferred for the above-mentioned
reason. Monodisperse polymers are generally prepared by fractionating a
polymer formed by radical polymerization and having a wide molecular
weight dispersity or by effecting living anion polymerization so as to be
monodisperse. Since the former fractionating method is complex, the latter
living anion polymerization method is desirably used. Some copolymers are
desirably formed by radical polymerization because some monomers are not
living anion polymerizable.
Where polymers of the invention are prepared by radical (co)polymerization,
radical polymerization of a monomer or monomers of the above-defined
formula(e) is first carried out in a conventional manner using a
polymerization initiator. Any of conventional polymerization initiators
may be used in a conventional amount. Preferred are organic peroxides,
especially organic peroxides having a 10-hour half-life temperature of 40
to 90.degree. C. such as lauroyl peroxide.
The radical polymerization is preferably carried out in organic solvents.
Useful organic solvents include aromatic hydrocarbon, cyclic ether,
aliphatic hydrocarbon solvents such as benzene, toluene, tetrahydrofuran
(THF), dioxane, tetrahydropyran, dimethoxyethane, n-hexane; and
cyclohexane and mixtures thereof. Acetone is most preferred. The organic
solvents may be used so as to give a monomer concentration of 10 to 50% by
weight.
Radical polymerization conditions may be properly adjusted. Typically,
reaction is carried out for about 3 to 10 hours at a temperature which is
20 to 50.degree. C. higher than the 10-hour half-life temperature of the
organic peroxide.
Where polymers of the invention are prepared by living anion
polymerization, well-known living anion polymerization initiators may be
used. Particularly when it is desired to obtain a monodisperse polymer,
organometallic compounds are preferably used among other living anion
polymerization initiators. Useful organometallic compounds are organic
alkali metal compounds such as n-butyl lithium, sec-butyl lithium,
tert-butyl lithium, naphthalene sodium, naphthalene potassium, anthracene
sodium, .alpha.-methylstyrenetetramerdi sodium, cumyl potassium, and cumyl
cesium. The amount of living anion polymerization initiator added is
determined from a design molecular weight (=weight of monomer/moles of
initiator).
Living anion polymerization of the monomers is generally carried out in
organic solvents. The organic solvents used herein are the same as
mentioned for the radical polymerization, with tetrahydrofuran being
especially preferred.
Adequate polymerization takes place when the monomers are present in a
concentration of 1 to 30% by weight. Reaction is preferably carried out by
agitating the reaction solution in high vacuum or in an inert gas
atmosphere such as argon and nitrogen. The reaction temperature may be
selected from a wide range from -78.degree. C. to the boiling point of the
reaction solution used. A temperature of -78.degree. C. to 0.degree. C. is
preferred for the tetrahydrofuran solvent and room temperature is
preferred for the benzene solvent.
Polymerization reaction proceeds for about 10 minutes to about 7 hours and
can be stopped by adding a stopper such as methanol, water and methyl
bromide to the reaction solution.
The living anion polymerization can produce a polymer having a molecular
weight dispersity which is monodisperse, that is, Mw/Mn=1.0 to 1.5 because
the monomer can be reacted 100% and the molecular weight be properly
adjusted.
It is noted that the weight average molecular weight (Mw) of a polymer can
be calculated from the weight of a monomer used and the moles (or number
of molecules) of an initiator and measured by a light scattering method.
The number average molecular weight (Mn) can be measured using a diaphragm
osmometer. The molecular structure can be readily acknowledged by infrared
(IR) absorption spectroscopy and .sup.1 H-NMR spectroscopy. The molecular
weight dispersity can be determined by gel permeation chromatography
(GPC).
One preferred process of preparing a polymer of the invention is in accord
with the reaction scheme shown below involving the steps of effecting
radical polymerization or living anion polymerization of monomers of
formulae (vi), (vii), and (v) to form a polymer of formula (18),
hydrolyzing the polymer, and protecting some of the hydroxyl groups
resulting from hydrolysis by chemical reaction with a first acid labile
group of formula (16) and a second acid labile group of formula (17), for
example.
##STR14##
In the above reaction scheme, tBu is tert-butyl, R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, n, m, p, q, r, and s are as previously defined.
In the above reaction scheme, a tert-butyl group of a polymer of formula
(18), preferably a polymer of formula (18) having a weight average
molecular weight of 3,000 to 300,000 and a molecular weight; dispersity of
1.0 to 1.5 is hydrolyzed to form a polyhydroxystyrene derivative of
formula (19). As shown by formulae (20) and (21), some of the hydroxyl
groups resulting from hydrolysis are successively protected with acid
labile groups represented by R.sup.2 and R.sup.3, thereby obtaining a
polymer of formula (21) which is monodisperse (that is, has a molecular
weight dispersity of 1.0 to 1.5) and has a weight average molecular weight
of 3,000 to 300,000.
In particular, for hydrolysis of a polymer of formula (18), more
specifically hydrolysis of a tert-butyl group which is a protective group
for its hydroxyl group, an appropriate amount of acid such as hydrochloric
acid and hydrobromic acid is added dropwise to a solution of the polymer
in a solvent mixture of dioxane, acetone, acetonitrile, benzene, water and
so forth. This procedure readily produces a hydroxyl-bearing
polyhydroxystyrene derivative of formula (19) having a controlled
molecular weight dispersity because neither cleavage of the polymer
backbone nor cross-linking reaction between molecules occurs during
reaction.
After the protective group for the hydroxyl group is detached by hydrolysis
as mentioned above, acid labile groups represented by R.sup.2 and R.sup.3
can be introduced through chemical reaction.
This reaction scheme is advantageous particularly when a polymer wherein
R.sup.2 is an alkoxyalkyl group is obtained. The alkoxyalkylation reaction
is effected by adding a hydrogen atom of a hydroxyl group of the
polyhydroxystyrene derivative of formula (19) to a vinyl group of an ether
compound of the following formula (22) in the presence of an acid
catalyst, thereby protecting some of hydroxyl groups of the
polyhydroxystyrene (in an amount of p mol per mol of the entire hydroxyl
group) with alkoxyalkyl groups.
##STR15##
R.sup.1, R.sup.4, R.sup.5, R.sup.15, R.sup.17, n, m, p, q, r, and s are as
previously defined, and R.sup.19 is a hydrogen atom or normal, branched or
cyclic alkyl group of 1 to 5 carbon atoms.
The ether compounds of formula (22) are vinyl ether, propenyl ether, and so
forth. This reaction is preferably carried out in a solvent such as
dimethylformamide, tetrahydrofuran, and dimethylacetamide. Exemplary acids
are hydrochloric acid, sulfuric acid, p-toluenesulfonic acid,
methanesulfonic acid, and pyridinium p-toluenesulfonate and they are
preferably used in an amount of 0.1 to 10 mol % per mol of the entire
hydroxyl group of the polyhydroxystyrene. The reaction temperature is
preferably room temperature to 60.degree. C. and the reaction time is
generally about 1 to 20 hours.
Where some of hydroxyl groups of the polyhydroxystyrene are
methoxymethylated, an alkali halide such as NaH and a halomethyl ether
such as chloromethyl ether are preferably reacted with the
polyhydroxystyrene in a solvent such as dimethylsulfoxide and
tetrahydrofuran. In this case, the amount of alkali halide used is
preferably determined such that methoxymethyl groups are introduced in an
appropriate amount per mol of the entire hydroxyl groups of the
polyhydroxystyrene. The reaction temperature is preferably 0 to 50.degree.
C. and the reaction time is generally about 1 to 20 hours.
After the alkoxyalkylation reaction, tert-butoxycarbonylation or
tert-butoxycarbonylmethylation reaction is carried out for introducing an
acid labile group R.sup.3.
The tert-butoxycarbonyl-introducing reaction may be carried out by reacting
the partially alkoxyalkylated polyhydroxystyrene with di-tert-butyl
dicarbonate in a solvent such as pyridine and tetrahydrofuran.
Di-tert-butyl dicarbonate is used herein in an amount to introduce q mol
of tert-butoxycarbonyl group per mol of the entire hydroxyl groups of the
polyhydroxystyrene. The reaction temperature is preferably room
temperature to 50.degree. C. and the reaction time is generally about 1/2
to 4 hours.
The tert-butoxycarbonylmethyl-introducing reaction may be carried out by
reacting the partially alkoxyalkylated polyhydroxystyrene with potassium
tert-butoxide and tert-butoxycarbonylmethyl bromide in a solvent such as
dimethyl sulfoxide and tetrahydrofuran. Potassium tert-butoxide is used
herein in an amount to introduce q mol of tert-butoxycarbonylmethyl group
per mol of the entire hydroxyl groups of the polyhydroxystyrene. The
amount of tert-butoxycarbonylmethyl bromide used is equimolar to the
potassium tert-butoxide. The reaction temperature is preferably room
temperature to 50.degree. C. and the reaction time is generally about 1/3
to 10 hours.
Also, the tetrahydropyranyl-incorporating reaction may be carried out by
reacting with dihydropyran in tetrahydrofuran. The
tetrahydrofuranyl-incorporating reaction may be carried out by reacting
with dihydrofuran in tetrahydrofuran. Alkylation reaction may be carried
out by reacting with isobutene in tetrahydrofuran. Trialkylsilylation
reaction may be carried out by reacting with a trialkylsilyl chloride in
the presence of imidazole. The reaction temperature is preferably room
temperature to 50.degree. C. and the reaction time is generally about 1 to
5 hours.
Among these reactions, it is advantageous to introduce a
tert-butoxycarbonyl or tert-butoxycarbonylmethyl group because a polymer
of the following general formula (24) can be produced thereby.
##STR16##
R.sup.1, R.sup.15, R.sup.16, R.sup.17, X, n, m, p, q, r, s, and a are as
previously defined.
The polymer of the invention can also be obtained by effecting radical
polymerization or living anion polymerization of a monomer of the
following formula (viii) to form a polymer of formula (25), hydrolyzing an
acetal group of the polymer, and protecting some of the resultant hydroxyl
groups with an appropriate acid labile group.
##STR17##
In the second aspect, the present invention provides a chemically amplified
positive resist composition. The resist composition is defined
in form (I) as comprising components (A), (B), and (C),
in form (II) as comprising components (A), (B), (C), and (D),
in form (III) as comprising components (A), (B), (C), and (E), and
in form (IV) as comprising components (A), (B), (C), (D), and (E).
Component (A) is an organic solvent.
Component (B) is the above-mentioned polymer as a base resin.
Component (C) is a photoacid generator.
Component (D) is a dissolution regulator in the form of a compound having a
weight average molecular weight of 100 to 1,000 and at least two phenolic
hydroxyl groups in a molecule, the hydrogen atom of the phenolic hydroxyl
group being replaced by an acid labile group in an average amount of 10 to
100% of the entire phenolic hydroxyl groups.
Component (E) is a dissolution regulator in the form of a compound having a
weight average molecular weight of more than 1,000 to 3,000 and a phenolic
hydroxyl group in a molecule, the hydrogen atom of the phenolic hydroxyl
group being partially replaced by an acid labile group in an average
amount of more than 0% to 60% of the entire phenolic hydroxyl groups.
The components other than (B) are described in detail.
The organic solvent (A) may be any desired one of organic solvents in which
a photoacid generator, base resin and dissolution regulator are soluble.
Exemplary organic solvents include ketones such as cyclohexanone and
methyl-2-n-amyl ketone; alcohols such as 3-methoxybutanol,
3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol;
ethers such as propylene glycol monomethyl ether, ethylene glycol
monomethyl ether, propylene glycol monoethyl ether, ethylene glycol
monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol
dimethyl ether; and esters such as propylene glycol monomethyl ether
acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl
pyruvate, butyl acetate, methyl 3-methoxypropionate, and ethyl
3-ethoxypropionate alone or in admixture of two or more. Among these
organic solvents, diethylene glycol dimethyl ether and 1-ethoxy-2-propanol
are preferred because the photoacid generator is most soluble therein.
The amount of the organic solvent used is preferably about 200 to 1,000
parts by weight, especially about 400 to 800 parts by weight per 100 parts
by weight of the base resin. With less than 200 parts of the organic
solvent, the respective components would be less miscible and film
formation be sometimes difficult. A composition containing more than 1,000
parts of the organic solvent would form a too thin resist film.
The photoacid generator (C) may be selected, for example, from onium salts,
sulfonated compounds, halo-compounds, and triazines. Onium salts and
sulfonated compounds are preferred, inter alia. Non-limiting examples of
the onium salt include triphenylsulfonium triflates and triphenylsulfonium
tosylates. Non-limiting examples of the sulfonated compound include
alkylsulfonates and azidosulfonates. The amount of the photoacid generator
added is preferably about 1 to 20 parts by weight, especially about 2 to
10 parts by weight per 100 parts by weight of the base resin.
To the resist composition of the invention, a dissolution regulator (D) may
be added. It is a compound having a weight average molecular weight of 100
to 1,000 and at least two phenolic hydroxyl groups in a molecule wherein
the hydrogen atom of the phenolic hydroxyl group is replaced by an acid
labile group in an average amount of 10 to 100% of the entire phenolic
hydroxyl groups. The compound has a weight average molecular weight of 100
to 1,000, preferably 150 to 800. The percent substitution of an acid
labile group for the hydrogen atom of the phenolic hydroxyl group is on
average at least 10%, preferably at least 30% of the entire phenolic
hydroxyl groups. With a substitution rate of less than 10%, edge roughness
occurs. The upper limit of substitution rate is 100%, preferably 80%.
Preferred examples of the phenolic hydroxyl group-bearing compound are
given below by formulae (4) to (14). In these compounds, the hydrogen atom
of the phenolic hydroxyl group is replaced by an acid labile group.
##STR18##
R.sup.8 and R.sup.9 are independently a hydrogen atom, normal or branched
alkyl or alkenyl group of 1 to 8 carbon atoms. R.sup.10 is a hydrogen
atom, normal or branched alkyl or alkenyl group of 1 to 8 carbon atoms or
--(R.sup.14).sub.z --COOH. R.sup.11 and R.sup.12 are independently an
alkylene group of 1 to 10 carbon atoms, arylene group, carbonyl group,
sulfonyl group, oxygen atom or sulfur atom. R.sup.13 is an alkyl or
alkenyl group of 1 to 8 carbon atoms, hydrogen atom, hydroxyl-substituted
phenyl group or hydroxyl-substituted naphthyl group. R.sup.14 is a normal
or branched alkylene group of 1 to 10 carbon atoms. Letter h is an integer
of 0 to 3, and z is equal to 0 or 1. Letters x, y, x', y', x", and y" are
such numbers in the range: x+y=8, x'+y'=5, and x"+y"=4 that at least one
hydroxyl group is contained in each phenyl skeleton.
Exemplary groups of R's are as follows. R.sup.8 and R.sup.9 may be hydrogen
atom, methyl, ethyl, propyl, butyl, ethynyl, and cyclohexyl. R.sup.10 may
be hydrogen atom, methyl, ethyl, propyl, butyl, and cyclohexyl as well as
--COOH and --CH.sub.2 COOH. R.sup.11 and R.sup.12 may be methylene,
ethylene, phenylene, carbonyl, sulfonyl, oxygen atom, and sulfur atom.
R.sup.13 may be methyl, ethyl, butyl, propyl, ethynyl, cyclohexyl,
hydrogen atom, hydroxyl-substituted phenyl group, and hydroxyl-substituted
naphthyl group.
Examples of the acid labile group for the dissolution regulator include
groups of formulae (16) and (17), tert-butyl, tetrahydropyranyl,
tetra-hydrofuranyl, trialkylsilyl, and .beta.-ketoalkyl groups.
The compounds having at least some phenolic hydroxyl groups replaced by
acid labile groups as dissolution regulators (D) may be used alone or in
admixture of two or more. The amount of this compound blended as
dissolution regulator (D) is preferably 0 to about 50 parts by weight,
more preferably about 5 to 50 parts by weight, most preferably about 10 to
30 parts by weight per 100 parts by weight of the base resin. Less than 5
parts of the compound would be too small to improve resolution. More than
50 parts of the compound would cause a loss of thickness of pattern film,
resulting in low resolution.
The dissolution regulator (D) defined above can be synthesized by
chemically reacting an acid labile group with a compound having a phenolic
hydroxyl group in a similar manner to the base resin.
The chemically amplified positives resist composition of the invention may
contain another dissolution regulator (E) instead of or in addition to the
dissolution regulator (D). The dissolution regulator (E) is a compound
having a weight average molecular weight of more than 1,000 to 3,000 and a
phenolic hydroxyl group in a molecule wherein the hydrogen atom of the
phenolic hydroxyl group is partially replaced by an acid labile group in
an average amount of more than 0% to 60%, preferably more than 0% to 40%
of the entire phenolic hydroxyl groups. A compound with a substitution
rate of 0% is less effective for dissolution control whereas a compound
with a substitution rate of less than 60% causes phase separation between
polymers and a loss of compatibility.
The compounds having some phenolic hydroxyl groups replaced by acid labile
groups as dissolution regulator (E) may be used alone or in admixture of
two or more. They are preferably compounds having a recurring unit of the
following general formula (15):
##STR19##
wherein R is an acid labile group, and letters b and c are numbers
satisfying 0<b/(b+c).ltoreq.0.6.
Examples of the acid labile group for the dissolution regulator include
alkoxyalkyl groups of formula (16), carbonyl-containing groups of formula
(17), tert-butyl, tetrahydropyranyl, trialkylsilyl, and .beta.-ketoalkyl
groups.
The amount of this compound blended as dissolution regulator (E) is
preferably 0 to about 50 parts by weight, more preferably about 1 to 50
parts by weight, most preferably about 1 to 30 parts by weight per 100
part by weight of the base resin. Less than 1 parts of the compound would
be too small to improve resolution. More than 50 parts of the compound
would cause a loss of thickness of pattern film, resulting in low
resolution.
The dissolution regulator (E) defined above can be synthesized by
chemically reacting an acid labile group with a compound having a phenolic
hydroxyl group in a similar manner to the base resin.
As mentioned above, the dissolution regulators (D) and (E) may be used
separately or in admixture.
The chemically amplified positive resist composition of the invention may
further contain (F) a basic compound as an additive. The basic compound
blended as additive (F) is preferably a compound capable of suppressing
the rate of diffusion of an acid resulting from the photoacid generator
into a resist film. Since the rate of diffusion of acid in the resist film
is suppressed by blending such a basic compound, there are obtained many
advantages including improved resolution, suppressed change of sensitivity
after exposure, reduced dependency on the substrate and environment,
improved latitude of exposure, and improved pattern profile. The basic
compound used herein encompasses primary, secondary and tertiary aliphatic
amines, mixed amines, aromatic amines, heterocyclic amines, nitrogenous
compounds having a carboxyl group, nitrogenous compounds having a sulfonyl
group, nitrogenous compounds having a hydroxyl group, nitrogenous
compounds having a hydroxyphenyl group, alcoholic nitrogenous compounds,
and amide derivatives.
Examples of the primary aliphatic amine include ammonia, methylamine,
ethylamine, propylamine, butylamine, pentylamine, amylamine, hexylamine,
heptylamine, octylamine, nonylamine, diacylamine, laurylamine, cetylamine,
methylenediamine, ethylenediamine, and tetraethylenediamine. Examples of
the secondary aliphatic amine include dimethylamine, diethylamine,
dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine,
dioctylamine, dinonylamine, didecylamine, dimethylmethylenediamine,
dimethylethylenediamine, and dimethyltetraethylenediamine. Examples of the
tertiary aliphatic amine include trimethylamine, triethylamine,
tripropylamine, tributylamine, tripentylamine, trihexylamine,
triheptylamine, trioctylamine, tetramethylmethylenediamine,
tetramethylethylenediamine, and tetramethyltetraethylenediamine.
Examples of the mixed amine include dimethylethylamine and
methylethylpropylamine. Examples of the aromatic and heterocyclic amines
include benzylamine, phenethylamine, benzyldimethylamine, aniline
derivatives (e.g., aniline, N-methylaniline, N-ethylaniline,
N-propylaniline, N,N-dimethylaniline, 2-methylaniline, 3-methylaniline,
4-methylaniline, ethylaniline, propylaniline, trimethylaniline,
4-nitroaniline, and dinitroaniline), toluidine derivatives (e.g.,
toluidine and N,N-dimethyltoluidine), quinoline, aminobenzoic acid,
N-phenylphenyltolylamine, N-methyldiphenylamine, triphenylamine,
phenylenediamine, naphthylamine, diaminonaphthalene, pyrrole derivatives
(e.g., pyrrole, methylpyrrole, dimethylpyrrole, and N-methylpyrrole),
imidazole derivatives (e.g., imidazole, 4-methylimidazole, and
4-methyl-2-phenylimidazole), oxazole derivatives, thiazole derivatives,
pyrazole derivatives, pyrrolidine derivatives (e.g., pyrrolidine,
N-methylpyrrolidone, and N-methylpyrrolidine), pyrroline derivatives,
pyridine derivatives (e.g., pyridine, methylpyridine, ethylpyridine,
propylpyridine, butylpyridine, 5-butyl-2-methylpyridine,
trimethylpyridine, triethylpyridine, phenylpyridine,
3-methyl-2-phenylpyridine, tert-butylpyridine, diphenylpyridine,
benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine,
1-methyl-2-pyridone, 4-pyrrolidinylpyridine, 1-methyl-4-phenylpyridine,
and 2-(1-ethylpropyl)pyridine), piperidine derivatives, pyrimidine
derivatives, purine derivatives, quinoline derivatives, carbazole
derivatives, indole derivatives, nicotinamide derivatives, adenosine
derivatives, adenine derivatives, thiabenzole, and diaminosulfone.
Examples of the nitrogenous compound having a carboxyl group include amino
acid derivatives (e.g., nicotinic acid, alanine, alginine, aspartic acid,
glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine,
methionine, phenylalanine, threonine, lysine, 3-aminopyrazine-2-carboxylic
acid, and methoxyalanine. Examples of the nitrogenous compound having a
sulfonyl group, nitrogenous compound having a hydroxyl group, nitrogenous
compound having a hydroxyphenyl group, and alcoholic nitrogenous compound
include 2-hydroxypyridine, aminocresole, thiamine naphthalene disulfonate,
pyridinesulfonic acid, ethanolamine, diethanolamine, trietharolamine,
diisopropylamine, triisopropylamine, tripropylamine, l-aminobutane-2-diol,
1-aminopropan-3-ol, and 1-aminobutane-2-diol. Examples of the amide
derivative include formamide, N-methylformamide, N,N-dimethylformamide,
acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, and
benzamide.
The amount of the basic compound blended is preferably 0 to 10 parts by
weight, more preferably 0.001 to 10 parts by weight, most preferably 0.01
to 1 part by weight per part by weight of 1he photoacid generator. Less
than 0.001 part of the basic compound would provide little additive
effect. More than 10 parts of the basic compound would adversely affect
resolution and sensitivity.
In the resist composition of the invention, there may be added optional
components, for example, surfactants for improving applicability and light
absorbing agents for reducing irregular reflection from the substrate.
These optional components are added in conventional amounts insofar as the
objects of the invention are not impaired. Examples of the surfactant
include perfluoroalkyl polyoxyethylene ethanol, fluorinated alkyl esters,
perfluoroalkylamine oxide, and perfluoroalkyl EO adducts. Exemplary Light
absorbing agents are diarylsulfoxide, diarylsulfone,
9,10-dimethylanthracene, and 9-fluorenone.
Any well-known lithography may be used to form a resist pattern from a
chemically amplified positive resist composition of the invention. For
example, the resist composition is spin coated onto a silicon wafer to a
thickness of 0.5 to 2.0 .mu.m, prebaked at 80 to 120.degree. C., exposed
to actinic radiation such as deep-ultraviolet radiation, electron beam,
and X-ray, and baked at 70 to 120.degree. C. for 30 to 200 seconds
(post-exposure baking=PEB), and developed with an aqueous base solution.
The resist composition of the invention is especially suitable for fine
patterning with deep-ultraviolet radiation of 254 to 193 nm and electron
beams.
There has been described a chemically amplified positive resist composition
comprising a specific polymer as a base resin. It is sensitive to actinic
radiation and improved in sensitivity, resolution, and plasma etching
resistance while the resulting resist pattern is well resistant to heat.
It has improved size control in that the resist pattern is relatively free
of overhang. Owing to these advantages, the resist composition of the
invention ensures that the resist material has reduced absorption at the
exposure wavelength of a KrF excimer laser and forms a fine pattern having
side walls perpendicular to the substrate. It is suitable as a fine
pattern-forming material for the manufacture of ultra-LSIs.
EXAMPLE
Examples of the present invention are given below by way of illustration
and not by way of limitation.
Synthesis Example 1
A 500-ml flask was charged with 1 gram of lauryl peroxide, 75 grams of
3-tert-butoxycarbonyloxy-4-hydroxystyrene, and 1,000 ml of acetone. The
flask was purged with nitrogen. The mixture was heated at 90.degree. C.
for 5 hours for polymerization reaction. At the end of polymerization
reaction, the reaction product was washed with methanol and dried,
obtaining a polymer of the rational formula shown below in a yield of 98%.
This polymer designated Polym 1 had a weight average molecular weight (Mw)
and dispersity (Mw/Mn) as shown in Table 1. On proton-NMR analysis, a peak
attributable to a tert-BOC group was observed at 1.5 ppm.
Synthesis Examples 2-13
Polymers designated Polym 2 to 13 were obtained by the same procedure as
Synthesis Example 1 except that the monomers shown below were used. The
polymers had a structure as shown by their rational formula and a weight
average molecular weight (Mw) and dispersity (Mw/Mn) as shown in Table 1.
Synthesis Example 2
3-tetrahydropyranyloxy-4-hydroxystyrene
Synthesis Example 3
3-tert-butoxycarbonyloxymethyl-4-hydroxystyrene
Synthesis Example 4
3-methoxyethoxy-4-hydroxystyrene
Synthesis Example 5
3-trimethylsilyl-4-hydroxystyrene
Synthesis Example 6
4-tert-butoxycarbonyloxy-3-hydroxystyrene
4-hydroxystyrene
Synthesis Example 7
4-tert-butoxycarbonyloxy-3-hydroxystyrene
3,4-dihydroxystyrene
Synthesis Example 8
3-tert-butoxycarbonyloxy-4-hydroxystyrene
3,4-dihydroxystyrene
4-hydroxystyrene
Synthesis Example 9
3-tert-butoxycarbonyloxy-4-hydroyxystyrene
4-hydroxystyrene
4-tetrapyranyloxystyrene
Synthesis Example 10
3-tert-butoxycarbonyloxy-4-hydroxystyrene
4-hydroxystyrene
3,4-di-tert-butoxycatbonyloxystyrene
Synthesis Example 11
3-tert-butoxycarbonyloxy-4-hydroxystyrene tert-butyl acrylate
Synthesis Example 12
4-tert-butoxycarbonyloxy-3-hydroxystyrene
3,4-dihydroxystyrene hydroxystyrene
Synthesis Example 13
4-tert-butoxycarbonyloxy-3-hydrocystyrene
3-tert-butoxycarbonyloxy-4-hydroxystyrene
3,4-dihydroxystyrene
4-hydroxystyrene
4-tert-butoxycarbonyloxystyrene
Synthesis Example 14
A 2-liter flask was charged with 700 ml of tetrahydrofuran as a solvent and
2.times.10.sup.-3 mol of sec-butyl lithium as an initiator. 40 grams of
3,4-di-tert-butoxystyrene was added to the flask contents at -78.degree.
C., which was agitated for 1 hour for polymerization. The reaction
solution was red. Polymerization was stopped by adding methanol to the
reaction solution.
The reaction solution was then poured into methanol whereupon the reaction
product precipitated. The precipitate was separated and dried, obtaining
39 grams of a white polymer which was poly(3,4-di-tert-butoxystyrene). The
polymer had a weight average molecular weight of 1.8.times.10.sup.4 g/mol
as measured by membrane osmometry. A GPC elution curve indicative of a
molecular weight distribution showed that the polymer was highly
monodisperse, that is, Mw/Mn=1.15.
In 900 ml of acetone was dissolved 30 grams of the thus obtained
poly(3,4-di-tert-butoxystyrene). A small amount of conc. sulfuric acid was
added to the solution at 60.degree. C., which was agitated for 7 hours.
The reaction solution was poured into water whereupon the polymer
precipitated. The precipitate was washed and dried, obtaining 20 grams of
a polymer. The polymer had a weight average molecular weight of
1.3.times.10.sup.4 g/mol. Since no peak attributable to a tert-butyl group
was observed on proton-NMR analysis, the polymer was
poly(3,4-dihydroxystyrene) having a narrow molecular weight dispersity.
In 500 ml of pyridine was dissolved 50 grams of the thus obtained
poly(3,4-dihydroxystyrene). With stirring at 45.degree. C. 18 grams of
di-tert-butyl dicarbonate was added to the solution. After 1 hour of
reaction, the reaction solution was added dropwise to 3 liters of water
whereupon a white solid precipitated. After filtration, the solid was
dissolved in 50 ml of acetone and added dropwise to 2 liters of water.
After filtration, the precipitate was dried in vacuum, obtaining a
polymer. This polymer designated Polym 14 had a t-BOC introduction of the
hydrogen atom of hydroxyl group of 20% as calculated from proton-NMR, a
;eight average molecular weight (Mw) and dispersity (Mw/Mn) as shown in
Table 1, and a GPC elution curve as shown in FIG. 1.
Synthesis Example 15
A 2-liter flask was charged with 700 ml of tetrahydrofuran as a solvent and
2.times.10.sup.-3 mol of sec-butyl lithium as an initiator. A mixture
containing 20 grams of 4-tert-butoxystyrene and 20 grams of
3,4-di-tert-butoxystyrene was added to the flask content at -78.degree.
C., which was agitated for 1 hour for polymerization. The reaction
solution was red. Polymerization was stopped by adding methanol to the
reaction solution.
The reaction solution was then poured into methanol whereupon the reaction
product precipitated. The precipitate was separated and dried, obtaining
39 grams of a polymer which was identified to be a random copolymer
consisting of 50% of 3,4-di-tert-butoxystyrene and 50% of
4-tert-butoxystyrene as analyzed by .sup.13 C-NMR. The polymer had a
weight average molecular weight of 1.8.times.10.sup.4 g/mol as measured by
membrane osmometry. A GPC elution curve indicative of a molecular weight
distribution showed that the polymer was highly monodisperse, that is,
Mw/Mn=1.15.
In 300 ml of acetone was dissolved 20 grams of the random copolymer of
3,4-di-tert-butoxystyrene and 4-tert-butoxystyrene. A small amount of
conc. sulfuric acid was added to the solution at 60.degree. C., which was
agitated for 6 hours. The reaction solution was poured into water
whereupon the polymer precipitated. The precipitate was washed and dried,
obtaining 16 grams of a polymer. The polymer had a weight average
molecular weight of 1.3.times.10.sup.4 g/mol. A GPC elution curve as shown
in FIG. 2 indicated that it was a highly monodisperse polymer. Since no
peak attributable to a tert-butyl group was observed on proton-NMR
analysis, the polymer was a copolymer of 3,4-dihydroxystyrene and
4-hydroxystyrene having a narrow molecular weight dispersity.
In 500 ml of tetrahydrofuran was dissolved 50 grams of the random copolymer
of 3,4-dihydroxystyrene and 4-hydroxystyrene. A catalytic amount of
p-toluenesulfonic acid was added. With stirring at 20.degree. C. 27 grams
of ethyl vinyl ether was added to the solution. After 1 hour of reaction,
the reaction solution was neutralized with conc. ammonia water and added
dropwise to 10 liters of water whereupon a white solid precipitated. After
filtration, the solid was dissolved in 500 ml of acetone and added
dropwise to 10 liters of water. After filtration, the precipitate was
dried in vacuum, obtaining a polymer. This random copolymer of
3,4-dihydroxystyrene and 4-hydroxystyrene had an ethoxyethyl introduction
of the hydrogen atom of hydroxyl group of 24% as calculated from .sup.13
C-NMR.
In 500 ml of pyridine was dissolved 50 grams of the partially
ethoxyethylated 3,4-dihydroxystyrene/4-hydroxystyrene random copolymer.
With stirring at 45.degree. C., 8 grams of di-tert-butyl dicarbonate was
added to the solution. After 1 hour of reaction, the reaction solution was
added dropwise to 3 liters of water whereupon a white solid precipitated.
After filtration, the solid was dissolved in 50 ml of acetone and added
dropwise to 2 liters of water. After filtration, the precipitate was dried
in vacuum, obtaining a polymer. This 3,4-dihydroxystyrene/4-hydroxystyrene
random copolymer, designated Polym 15, had an ethoxyethyl introduction of
the hydrogen atom of hydroxyl group of 24% and a t-BOC introduction of 11%
as calculated from proton-NMR, and its weight average molecular weight
(Mw) and dispersity (Mw/Mn) were as shown in Table 1.
Synthesis Examples 16-22
Polymers designated Polym 16 to 22 were obtained by the same procedure as
Synthesis Example 14 or 15 except that the monomers shown below were used.
The polymers had a structure as shown by their rational formula and a
weight average molecular weight (Mw) and dispersity (Mw/Mn) as shown in
Table 1.
Synthesis Example 16
3,4-diethoxyethoxystyrene
3,4-dihydroxystyrene
Synthesis Example 17
2,3,4-tri-tert-butoxycarbonyloxystyrene
2,3,4-trihydroxystyrene
Synthesis Example 18
3,4-di-tert-butoxycarbonylmethyloxystyrene
3,4-dihydroxystyrene
Synthesis Example 19
3,4-di-tert-butoxycarbonyloxystyrene
3,4-dihydroxystyrene
4-hydroxystyrene
4-ethoxyethoxystyrene
Synthesis Example 20
3,4-di-tert-butoxycarbonyloxystalrene
3,4-dihydroxystyrene
3,4-ethoxyethoxystyrene
Synthesis Example 21
3,4-di-tert-butoxycarbonylmethyloxystyrene
3,4-dihydroxystyrene
3,4-diethoxypropoxystyrene
Synthesis Example 22
3,4-di-tert-butoxycarbonyloxystxrene
3,4-dihydroxystyrene
3,4-di-n-butoxyethoxystyrene
##STR20##
TABLE 1
__________________________________________________________________________
Weight
average
Molecular
molecular
weight
Synthesis Compositional ratio
weight
dispersity
Example
Designation
p t q r s (Mw) (Mw/Mn)
__________________________________________________________________________
1 Polym 1
1.0 13,400
1.78
2 Polym 2
1.0 14,000
2.25
3 Polym 3
1.0 15,000
2.00
4 Polym 4
1.0 12,000
1.85
5 Polym 5
1.0 12,000
1.65
6 Polym 6
1.0 14,500
1.85
7 Polym 7
0.2 0.8 14,000
2.18
8 Polym 8
0.2 0.5
0.3 14,000
1.85
9 Polym 9
0.1 0.8
0.1 12,000
1.60
10 Polym 10
0.1 0.8
0.1 11,000
1.80
11 Polym 11
0.5 0.5
14,000
2.25
12 Polym 12
0.2 0.75 0.05
12,000
1.80
13 Polym 13
0.05 0.6
0.05 14,000
1.90
0.1 0.2
14 Polym 14 0.2
0.8 13,000
1.15
15 Polym 15 0.055
0.325
0.055 13,000
1.15
0.12
0.325
0.12
16 Polym 16 0.3
0.7 12,000
1.10
17 Polym 17 0.2
0.8 14,000
1.15
18 Polym 18 0.23
0.77 13,000
1.10
19 Polym 19 0.07
0.5
0.3 14,000
1.15
0.13
20 Polym 20 0.1
0.7
0.2 13,000
1.10
21 Polym 21 0.1
0.8
0.1 14,000
1.15
22 Polym 22 0.1
0.8
0.1 14,000
1.10
__________________________________________________________________________
Examples and Comparative Examples
Liquid resist compositions were prepared by dissolving a polymer as a base
resin, a photoacid generator, a dissolution regulator in a solvent in
accordance with the formulation shown in Table 2. Each of the compositions
was passed through a 0.2-.mu.m Teflone.RTM. filter.
The polymers used were those obtained in Synthesis Examples 1 to 22, that
is, Polym 1 to Polym 22.
The photoacid generators used were PAG1 to PAG10 shown below.
The dissolution regulators used were DRR1 to DRR14 and DRR1' to DRR8' shown
below.
The solvents used were
diethylene glycol dimethyl ether (DGLM),
1-ethoxy-2-propanol (EIPA),
methyl 2-n-amyl ketone (MAK),
propylene glycol monomethyl acetate (PGMMA),
propylene glycol monoethyl acetate (PGMEA), and
ethyl lactate/butyl acetate (EL/BA).
For comparison purposes, a liquid resist composition was similarly prepared
using a polymer designated Polym 23 as a base resin.
##STR21##
Each liquid resist composition was then spin coated onto a silicon wafer to
form a coating of 0.8 .mu.m thick. With the silicon wafer rested on a hot
plate at 100.degree. C., the coating was pre-baked for 120 seconds. The
film was 35 exposed to a pattern of light by means of an excimer laser
stepper model NSR-2005EX8A (manufactured by Nikon K.K., numerical aperture
NA=0.5), baked at 90.degree. C. for 60 seconds, and developed with an
aqueous solution of 2.38% tetramethylammonium hydroxide, obtaining a
positive pattern.
The resulting resist pattern was evaluated as follows.
First, sensitivity (Eth value) was determined. Provided that the exposure
quantity with which the top and bottom of a 0.35-.mu.m line-and-space
pattern were resolved at 1:1 was the optimum exposure (sensitivity Eop),
the minimum line width of a line-and-space pattern which was recognized
separate at this exposure was the resolution of a test resist. The
configuration of the resist pattern resolved was observed under a scanning
electron microscope. The edge roughness of a 0.25 .mu.m line-and-space
pattern was also observed under a scanning electron microscope.
The results are shown in Table 2.
##STR22##
TABLE 2
__________________________________________________________________________
Resist composition (pbw in parentheses) Edge
Photoacid
Dissolution
Basic Eop Resolution
roughness
Example
Base resin
generator
regulator
compound Solvent
(mJ/cm.sup.2)
(.mu.m)
(mm)
__________________________________________________________________________
1 Polym 1 (80)
PAG1 (3)
-- -- DGLM (300)
10 0.28 13
2 Polym 2 (80)
PAG2 (3)
-- -- DGLM (300)
28 0.30 15
3 Polym 3 (80)
PAG3 (4)
-- -- DGLM (300)
24 0.28 16
4 Polym 4 (80)
PAG4 (3)
-- -- DGLM (300)
30 0.30 15
5 Polym 5 (80)
PAG5 (4)
-- -- DGLM (300)
18 0.28 15
6 Polym 6 (80)
PAG1 (4)
DRR2 (14)
-- DGLM (300)
9 0.28 13
7 Polym 7 (80)
PAG2 (3)
DRR1 (14)
-- DGLM (300)
30 0.28 12
8 Polym 8 (80)
PAG2 (4)
DRR1 (14)
-- EIPA (300)
8 0.28 11
9 Polym 9 (80)
PAG2 (3)
DRR2 (14)
-- DGLM (300)
15 0.28 13
10 Polym 10 (80)
PAG1 (4)
DRR2 (14)
-- DGLM (300)
25 0.26 12
11 Polym 11 (80)
PAG6 (3)
-- -- MAK (300)
23 0.28 12
12 Polym 12 (80)
PAG7 (3)
DRR1 (14)
-- DGLM (300)
19 0.24 15
13 Polym 13 (80)
PAG8 (3)
DRR1 (14)
-- DGLM (300)
10 0.22 11
14 Polym 14 (80)
PAG9 (3)
DRR2 (14)
-- DGLM (300)
30 0.22 12
15 Polym 15 (80)
PAG10 (3)
DRR2 (14)
-- DGLM (300)
25 0.22 11
16 Polym 16 (80)
PAG1 (3)
-- -- PGMEA (300)
15 0.22 10
17 Polym 17 (80)
PAG4 (3)
DRR1' (4)
-- PGMEA (300)
10 0.22 12
18 Polym 18 (80)
PAG3 (3)
-- -- PGMEA (300)
13 0.22 12
19 Polym 19 (86)
PAG1 (3)
DRR5' (4)
-- PGMEA (300)
20 0.22 11
20 Polym 20 (80)
PAG1 (3)
-- -- PGMEA (300)
10 0.22 14
21 Polym 21 (80)
PAG4 (3)
DRR7' (4)
-- PGMEA (300)
14 0.22 10
22 Polym 22 (80)
PAG1 (3)
-- -- PGMEA (300)
10 0.22 12
__________________________________________________________________________
Resist composition (pbw in parentheses) Edge
Photoacid Basic Eop Resolution
roughness
Example
Base resin
generator
Dissolution regulator
compound Solvent
(mJ/cm.sup.2)
(.mu.m)
(mm)
__________________________________________________________________________
23 Polym 16 (80)
PAG1 (4)
DRR1 (4)
-- -- PGMEA (300)
13 0.24 13
24 Polym 16 (80)
PAG2 (4)
DRR1 (16)
DRR2' (4)
-- PGMEA (300)
20 0.24 10
25 Polym 16 (80)
PAG4 (4)
DRR3 (4)
-- -- PGMEA (300)
15 0.24 13
26 Polym 14 (80)
PAG1 (4)
DRR4 (4)
-- -- PGMEA (300)
10 0.22 13
27 Polym 14 (80)
PAG2 (4)
DRR5 (4)
-- -- PGMEA (300)
5 0.22 13
28 Polym 14 (80)
PAG3 (4)
DRR6 (4)
-- -- DGLM (300)
15 0.22 13
29 Polym 15 (80)
PAG1 (4)
DRR2 (16)
DRR7' (4)
-- EL/BA (300)
20 0.22 10
30 Polym 19 (80)
PAG2 (4)
DRR3 (16)
DRR8' (4)
-- PGMEA (300)
15 0.22 10
31 Polym 19 (80)
PAG3 (4)
DRR4 (16)
DRR1' (4)
-- DGLM (300)
20 0.22 11
32 Polym 16 (80)
PAG1 (4)
DRR5 (16)
DRR2' (4)
-- DGLM (300)
10 0.22 10
33 Polym 18 (80)
PAG3 (4)
DRR11 (16)
DRR3' (4)
-- DGLM (300)
20 0.22 10
34 Polym 20 (80)
PAG1 (4)
DRR6 (16)
DRR4' (4)
-- DGLM (300)
10 0.22 10
35 Polym 16 (80)
PAG1 (4)
DRR7 (16)
DRR5' (4)
-- DGLM (300)
8 0.22 10
36 Polym 20 (80)
PAG2 (4)
DRR8 (16)
DRR6' (4)
-- DGLM (300)
15 0.22 10
37 Polym 16 (80)
PAG4 (4)
DRR9 (16)
DRR7' (4)
-- DGLM (300)
20 0.22 9
38 Polym 16 (80)
PAG5 (4)
DRR10 (16)
DRR8' (4)
-- DGLM (300)
30 0.22 9
39 Polym 16 (80)
PAG1 (3.5)
DRR12 (16)
DRR8' (4)
-- DGLM (300)
20 0.22 10
PAG8 (0.5)
40 Polym 19 (80)
PAG3 (4)
DRR13 (16)
DRR1' (4)
-- DGLM (300)
15 0.22 10
41 Polym 19 (80)
PAG4 (4)
DRR14 (16)
DRR2' (4)
-- PGMMA (300)
20 0.22 10
42 Polym 19 (80)
PAG2 (4)
DRR1 (1.6)
DRR3' (4)
-- PGMMA (300)
25 0.22 10
DRR12 (4)
43 Polym 16 (80)
PAG1 (4)
DRR7 (4)
-- tetraethylenediamine
PGMEA (300)
25 0.22 8
(0.2)
44 Polym 16 (80)
PAG7 (4)
DRR2 (16)
DRR7' (4)
dimethylethylene-
PGMEA (300)
20 0.22 8
diamine
(0.2)
45 Polym 16 (80)
PAG1 (3.5)
DRR12 (16)
DRR8' (4)
tetramethyl-
PGMEA (300)
25 0.22 8
PAG8 (0.5) ethylenediamine
(0.2)
46 Polym 16 (80)
PAG1 (4)
DRR4 (16)
DRR8' (4)
methylethylpropylamine
PGMEA (300)
30 0.22 6
(0.2)
47 Polym 16 (80)
PAG1 (4)
DRR2 (16)
DRR7' (4)
aniline PGMEA (300)
20 0.22 8
(0.2)
48 Polym 16 (80)
PAG4 (4)
DRR13 (16)
DRR7' (4)
piperidine PGMEA (300)
15 0.22 8
(0.2)
49 Polym 16 (80)
PAG1 (4)
DRR2 (16)
DRR3' (4)
N-methylpyrrolidone
PGMEA (300)
20 0.22 8
(0.2)
50 Polym 22 (80)
PAG1 (4)
DR1 (16)
DRR3' (4)
purine PGMEA (300)
15 0.22 8
DRR12 (4) (0.2)
51 Polym 19 (80)
PAG1 (4)
DRR2 (16)
DRR7' (4)
alanine PGMEA (300)
20 0.22 6
(0.2)
52 Polym 19 (80)
PAG1 (4)
DRR9 (16)
DRR7' (4)
pyridinesulfonic acid
PGMEA (300)
20 0.22 6
(0.2)
53 Polym 21 (80)
PAG4 (4)
DRR9 (16)
DRR7" (4)
2-hydroxypyridine
PGMEA (300)
15 0.20 6
(0.2)
54 Polym 21 (80)
PAG1 (4)
DRR2 (16)
DRR1' (4)
2-amino-p-cresol
PGMEA (300)
20 0.22 6
(0.2)
55 Polym 16 (80)
PAG1 (4)
DRR1 (4)
-- triethanolamine
PGMEA (300)
10 0.20 6
(0.2)
56 Polym 16 (80)
PAG1 (4)
DRR2 (16)
DRR8 (4)
N,N-dimethylacetamide
PGMEA (300)
15 0.22 6
(0.2)
__________________________________________________________________________
TABLE 3
__________________________________________________________________________
Resist composition (pbw in parentheses)
Comparative Photoacid
Dissolution Eop Resolution
Example
Base resin
generator
regulator
Solvent
(mJ/cm.sup.2)
(.mu.m)
__________________________________________________________________________
1 Polym23(80)
PAG1(3)
DRR1(14)
DGLM(300)
25 0.45
2 Polym23(80)
PAG2(3)
DRR1(14)
DGLM(300)
45 0.50
__________________________________________________________________________
It is evident that chemically amplified positive resist compositions within
the scope of the invention have high sensitivity and high resolution and
afford patterned resist films which have a well-defined profile, improved
size control, plasma etching resistance, and heat resistance.
Japanese Patent Application No. 7-111189/1995 is incorporated herein by
reference.
Although some preferred embodiments have been described, many modifications
and variations may be made thereto in the light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as specifically
described.
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